The present invention relates to a bit adapter and, more particularly, to a quick-release bit adapter allowing quick release of a bit.
U.S. Pat. No. 5,934,384 discloses a transmission shaft and a bit mounting arrangement for a motor-driven hand drill. The transmission shaft includes a coupling hole in a front end thereof for coupling with a bit. A coupling rod extends from a rear end of the transmission shaft for engaging with a motor-driven hand drill. A chuck is mounted on the front end of the transmission shaft. A compression spring pushes a stop member to engage with cuts of the bit to fix the bit, preventing the bit from falling out of the coupling hole. Furthermore, a magnet is mounted in the coupling hole. The chuck is moved rearward to disengage from the bit when it is desired to remove the bit. In this case, the bit is still attracted by the magnet, preventing the bit from being disengaged from the coupling hole under the action of gravity.
However, the front end of the bit exposed outside of the coupling hole is relatively short, such that the user has to overcome the magnetic attraction of the magnet by tightly gripping the front end of the bit by the finger tips and forcibly moving the bit outward, which is laborsome. Furthermore, the front ends of the bits of different sizes differ from each other in size. Thus, it is difficult for the user to grip and apply force to the front ends of bits of small sizes due to small contact surfaces with the finger tips of the user, resulting in difficulties in removing the bit. Furthermore, the hand of the user is often stained with oil, leading to small friction between the finger tips of the user and the front end of the bit and causing difficulties in removing the bit. A pair of pliers has to be used to clamp and remove the bit, causing trouble to users frequently using the transmission shaft or to professional workers during replacement of bits. Furthermore, the chuck mounted around the front end of the transmission shaft increases the overall outer diameter of the transmission shaft, such that the transmission shaft can not reach small holes. In some cases, the chuck is impinged by an inner periphery of a small hole and loses its clamping function, resulting in hazards during working. Thus, the transmission shaft and the bit mounting arrangement are inconvenient and unsafe.
Thus, a need exists for a novel quick-release bit adapter allowing quick release of a bit while providing enhanced safety during use.